Some internal combustion engines utilize a compression device such as a turbocharger to increase engine torque/power output density. In one example, a turbocharger may include a compressor and a turbine connected by a drive shaft, where the turbine is coupled to an exhaust manifold side and the compressor is coupled to an intake manifold side of an engine. In this way, the exhaust-driven turbine supplies energy to the compressor to increase the pressure (e.g. boost, or boost pressure) in the intake manifold and to increase the flow of air into the engine. The boost may be controlled by adjusting the amount of gas reaching the turbine, for example with a wastegate. A wastegate valve may be controlled based on operating conditions to achieve the desired boost. A sensor indicating the state of the wastegate may be provided, such as a position sensor indicating the position of the wastegate valve. In some examples, the wastegate valve is actuated pneumatically, while in other examples the wastegate valve is actuated electronically, for example by an electric motor.
U.S. Pat. No. 8,397,499 describes a system for controlling a turbocharged engine. The responsiveness of boost control is increased by adjusting both an intake throttle and a wastegate of a turbocharger to control boost levels supplied to the engine. The control system utilizes a plurality of feedback and feed-forward mechanisms to reduce error, including measurements of throttle inlet pressure (TIP) to account for disturbances caused by movement the intake throttle and to separate these disturbances from other effects.
In other approaches, wastegate control systems utilize both inner and outer loop control to facilitate positioning of a wastegate valve and thus provide desired boost levels to an engine. The outer loop control may implement desired boost levels, while the inner loop control may include a closed-loop control mechanism which provides faster wastegate control dynamics by controlling the wastegate valve (e.g., wastegate valve position) by issuing commands to a wastegate valve actuator.
The inventors herein have recognized an issue with such approaches. When operation of a sensor indicating the state (e.g., position) of an associated wastegate valve becomes degraded, feedback available for the inner loop control mechanism is no longer available. Thus, accurate boost levels may not delivered to an engine. Although the wastegate valve may be held at an at least partially open position to protect engine components from damage, sufficient boost levels cannot be delivered to the engine at certain load ranges.
Systems and methods for controlling a wastegate in the presence of a degraded wastegate valve state sensor.
In one example, responsive to feedback from a wastegate valve sensor being unavailable, a wastegate valve is moved to an at least partially open position in part via exhaust pressures responsive to a desired boost being within a first range. Responsive to feedback from the wastegate valve sensor being unavailable, the wastegate valve is moved toward a fully closed position at a rate responsive to boost pressure dynamics responsive to the desired boost being within a second, different range.
In this way, sufficient boost may be provided to an engine when feedback from a wastegate valve sensor is unavailable. Thus, the technical result is achieved by these actions.
The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.